Opiate abuse and HIV-1 have been described as two linked global health crises, and despite the advent of anti-retroviral therapy, abuse of opiates has been shown to result in increased neurologic and cognitive deficits. Using the morphine-dependent rhesus macaques (RM) infected with CCR5-utilizing SIVR71/17E we recapitulated the human syndrome demonstrating augmentation of neuropathology & neuroinflammation and rapid disease progression compared with SIV-infected controls. Mortality in these rapid progressors was associated with robust viral replication in both the periphery & the brain. MicroRNA (miR)-mediated regulation of disease pathogenesis represents an evolving area of research that has ramifications for identification of potential therapeutic targets for various neurodegenerative disorders for which currently there exists no cure. Based on the similarities between the chronology of lentiviral infection in humans and macaques, the SIV/RM model offers a unique platform to perform controlled studies on the role of morphine in potentiating disease pathogenesis. The goal of the present application is to address how interactions between morphine & SIV in the acute phase of infection impact disease outcome in the chronic stage in the context of miR-mediated regulation of neurotoxicity. The innovative aspects of this proposal are based on our unique observation that in chronically (SIV)-infected RMs, morphine mediated potentiation of neuropathogenesis correlates with dysregulation of miRs, with specific upregulation of miR-29b (that is also upregulated in Alzheimer's & Parkinsons diseases) in both the peripheral blood mononuclear cells (PBMCs) as well as post mortem brain tissue. The hypotheses to be tested are that: a) morphine-mediated potentiation of SIV neuropathogenesis involves, in part, upregulation of miR-29b during the early (acute phase) of infection and, b) based on target identification using computer algorithms upregulation of miR-29b is critical for regulating genes controlling neuronal survival such as the platelet-derive growth factor (PDGF) and its receptor (PDGF-R) dyad. Specific Aim 1 will be aimed at tracking morphine-mediated dysregulation of miR profiles (with emphasis on miR-29b) in the periphery & CNS of SIV-infected macaques during acute (14d pi) infection. These will be compared miR data obtained from the historical archived tissues of chronically infected RMs [ongoing parent study]. Specific Aim 2 will test the hypothesis that morphine-induced alteration in miR-29b targets the expression of neurotropic factors such as platelet-derived growth factor (PDGF) and its receptor, culminating into increased neuronal apoptosis.